State Banks are great for throwing conferences and keeping otherwise unemployable academics from littering the pavement as members of the homeless class. State owned institutions typically have an understood state mandate of protection and therefore cheaper borrowing. Fannie Mae and Freddie Mac are examples of this. Lending is often a commodity business and the cheapest money wins. Gresham's law, whereby bad money crowds out good money in banking markets usually means the state enterprise with cheap capital ends up dominating the sectors they are involved in. In the US Fannie Mae and Freddie mac ended up with +70% of the US mortgage market. The role of a bank is allocating capital. The role of the state is insuring the rights of its citizens by upholding the law. These roles do not explicitly or implicitly overlap.